Swim fins are devices that substantially increase the surface area of the naked foot thereby increasing the propulsive force of the legs. If used properly swim fins can conserve a diver's energy and facilitate underwater movement by becoming powerful extensions of a diver's body. In fact, fins can be so effective that arms and hands are not necessarily needed for propulsion when skin or scuba diving. However, few things feel as awkward as trying to walk while wearing swim fins due to the extended length of the fins which are cumbersome and can be potentially dangerous while walking.
To overcome this problem various swim fins have been proposed which provide a more natural and safer ambulatory motion. This is achieved by removing the blade portion from the front of the swim-fin. However, many of these proposals include complex pivoting devices and/or locking mechanisms that may corrode or malfunction during use. For example, U.S. Pat. No. 5,292,272 (Grim) discloses an open-heel swim fin having a pivoting fin which when retracted permits the fin blade to be positioned at a 90.degree. angle to the longitudinal axis of the foot. The fin blade pivots directly at the toe of the foot pocket, yet walking is still difficult because the upright blade increases resistance when walking or wading in shallow water. Likewise, U.S. Pat. No. 4,981,454 (Klein) discloses an open-heel swim fin having a retractable fin blade that pivots near the arch of the 10 foot. This pivoting allows for the fin to rise above the instep of the foot and positioned adjacent and parallel to the leg.
This prevents an awkward upright blade at the toe of the foot pocket but the fin blade is still in a cumbersome position which reduces flexibility when walking. U.S. Pat. No. 4,752,259 (Tackett et al.) discloses another embodiment of an open-heel model having a retractable fin wherein the surface area of the fin blade is bifurcated. The frontal end portion of the fin blade pivots upon itself either over or under the foot to facilitate walking. However, only a portion of the blade retracts leaving a substantial length of the fin blade extending longitudinally beyond the user's foot which impedes natural ambulation.
Accordingly, there is a need for a more reliable amphibious swim shoe that can be worn comfortably on land or wading in shallow water and can be easily converted into a swim fin without the disadvantages of complicated pivoting mechanisms, reduced flexibility of movement or malfunctioning locking mechanisms.